Piston



Aug. 2, 1927.

A. G. DUNBAR PISTQN Filed Dec. 5. 925

Cil

Patented Aug. 2, 1927.

UNITED STATES ALEXANDER GARDEN rDUNBAR, 0F GLASGOW, SCOTLAND.

IPISTON.

Application yfiled December 5, 1925, Serial No.

VThis invention has reference to steam engine pistons, )ump pistons, internal combustion engine pistons and other pistons and has for` its object to provide an improved packing which will have a greater useful life than the packing rings usually employed for such purposes. f

A further object of my invention is to provide improvements designed to minimize friction of the p-iston packing on the Vcylinder wall.

A further object of my invention consists in providing improvements designed to maintain a tight joint between the piston and packing and to minimize friction between the packing and piston so as to permit the packing to take up wear.

Those and other improvements will be vhereafter described and claimed.

According to my 'invention a piston is provided with one or more annular grooves and into each groove is litted a packing comprising a plurality of sections one or more of which is, or are, spring loaded so as to force same outwards, and the shape of the sections such that the spring influenced section, or sections, by the action of an inclined plane forces, or force, the other section, or sections, outwards.

Said sections may be provided with a groove on the periphery thereof to receive a lubricating packing of hard graphite or the like.

The sides of the annular recess in the piston into which the sections are iitted are' preferably grooved to receivepacking rings which bear on the sides of the sections, helical or other springs being preferably provided to force such rings against the sides of the sections.` y

On the annexed sheet of drawings is illustrated a preferred embodiment of my invention and whereon:

Figure l illustrates an elevation of the improved packing.

Figure 2 is an end elevation thereof.

Figure 3 illustrates a piston partly in section fitted with the improved packing and Figure l is a section on the line 4 4 Figure 3.

iThe packing illustrated consists of four sections or sectors a, c1 and b, b1, the seetions a, al being of a` wedge shape, i. e., having opposite sides inclined as indicated. Those sections are forced outwards with respect to each other by two or more helical 73,485, and in Great' Britain January 9, 1925.

springs c, c1 located between said sections and'held under tension.

The other two sections b, b1 are shaped as illustrated to accommodate the sections a, al.

The spring loaded sections provide a considerably'smaller portion of the periphery of the packing than the other-two sections.

Each section is provided with a groove Z onitsperiphery, such grooves, when the .sections are assembled forming an annular recess into which a packing of hard graphite or the like Z1 is inserted.

Projecting pins a? on sections ci, al, serve to maintain the ends of the springs c, c1 in position and the projections b2 on sections b1 serve to prevent the centre of the springs arching outwards.

Such packing formed by the assembled sections is inserted in an annular groove formed in the piston head, said groove being cut considerably deeper than is necessary to accommodate packing rings of usual construction.

' In Figures 3 and 4L is shown a piston cl provided with three annular grooves c and in each of which is inserted a packing similar to thatshown in Figures l and 2.

In order to maintain the packing tightly in the piston grooves and also to permit of expansion, the sides of said grooves are provided with annular recesses g into which are'v inserted packing rings a which bear on the sides ofthe sections a, al ando, b1, small helical springs i, or other springs being provided to force the rings against the sides of said sections. i

Said rings are made in halves to enable same to be inserted in the grooves, the halves being thereafter joined by any suitable means.

' In operation the spring loaded members a, al are forced outwards with respect to each other by the springs c, c1 and by reason of the co-acting inclined faces the other two members Z), are likewise forced outwards with respect to each other and by such means all wear of the sections and cylinder is taken up automatically.

By reason of the angles of said inclined faces the spring loaded members a, all have a greater travel than the others and the wear on their surface regulates the movement of all four sections. v

The graphite packing serves as a lubril eny leakage between the sections and the sides of the annular recesses into which they are fitted.

The co-acting sides ot the sections may be curved.

What I claim is 1. A packing ii'or pistons comprising two diametrically opposite segmental sections el' wedge formation, two helical parallel springs acting on said sections, and two diametrically opposite segments to eo-operate with said wedge segmental sections.

2. ln lpistons a packing comprising 'tour segmental sections accommodated in relatively deep annular recess provided in the piston, two of said segmental sections being of wedge like formation and the other two shaped to co-operate therewith, spring means acting on said wedge sections, and packing rings located in the Walls oi.n said recess and bearing on the segments.

3. ln pistons, a packing comprising four segmental sections accommodated wit-hin a relatively deep annular recess, two diametrically opposite sections being ofwedge formation and the other two shaped to cooperate therewith, spring means acting on said Wedge sections, packing rings located in annular recesses formed in the walls oi said groove, and spring means bearing on 30 said rings. f y V 4. In pistons, a packing comprising av plurality'of sections accommodated within f a deep annular groove in the piston, at least one of said sections being of wedge 'forma-35 tion, and the others shaped to cor-operatel l therewith, springmeans acting on a wedge section and packing located in the Walls olil the annular recess and bearing on the said sections shaped to accommodate the wedge sei-tiens helical sgrings extending between said Wedge shape sec-tions and tending to force them apart, and means to prev-ent the said springs arching outwards.

ALEX. s. DUNBiin. 

